Thin film magnetic head

ABSTRACT

A thin film magnetic head comprising a substrate, a lower magnetic pole provided on the substrate, a write gap layer located on the lower magnetic pole, and an upper magnetic pole located on the gap layer, the upper magnetic pole including a plating base layer in contact with the gap layer, wherein the plating base layer of the upper magnetic pole is made of a magnetic film having a saturation magnetic flux density of 1.2 T or larger. The thin film magnetic head has an increased recording density, and is adapted to recording at an increased frequency.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a thin film magnetic head and,particularly, to a thin film magnetic head characterized by theconstruction of its plating base layer for providing a magnetic polecore of a thin film magnetic head of an induction type constituting ahard disc drive (HDD) with a high saturation magnetic flux density.

[0003] 2. Description of the Related Art

[0004] Recent hard disc drives, which are external storage devices forcomputers, have an increasing recording density, and comprise a magnetichead with small elements. Also, recent recording mediums have anincreasing coercive force. Under the circumstances, a magnetic headcapable of adequately writing records to such a recording medium havinga high coercive force are demanded.

[0005] In inductive thin film magnetic heads, a thin film of Ni-Fe alloyis commonly used as a material for a write magnetic pole. Most of thewrite magnetic poles have a two-layer structure of a layer of Ni₅₀Fe₅₀,i.e., 50 permalloy, provided on a read gap and having a saturationmagnetic flux density B_(S) of the order of 1.5 teslas (T) and athickness of the order of 1 micrometer, and a layer of Ni₈₀Fe₂₀, i.e.,80 permalloy, laminated thereon and having a thickness of 1 to 4micrometers. This is for the sake of ensuring sufficient recordingproperties at a strong magnetic field by placing a magnetic materialhaving a saturation magnetic flux density B_(S) higher than 80 permalloynear an upper magnetic pole gap which is the point for finally writingon a recording medium.

[0006] A practical magnetic pole core, which is made up entirely of 50permalloy having a B_(S) nearly equal to 1.5 T, is known. However, since50 permalloy has a large magnetostriction, there is a possibility thatthe 50 permalloy material is strained during processing, and thisdegrades the magnetic properties of a magnetic pole core.

[0007] Referring to FIGS. 6A to 6C, a process for manufacturing aconventional writing thin film magnetic head is described.

[0008] As shown in FIG. 6A, a plating base layer 32 of Ni₈₀Fe₂₀ and alower magnetic pole layer 33 of Ni₈₀Fe₂₀ are successively formed on aTiC substrate 31 provided with an Al₂O₃ film (not shown) (also calledAl₂O₃—TiC substrate). The surface of the magnetic pole layer 33 is thenplanarized, and a write gap layer 34 consisting of Al₂O₃ or the like isprovided thereon by a sputtering process. There is a case where thewrite gap layer 34 is subsequently patterned together with the lowermagnetic pole layer 33 of Ni₈₀Fe₂₀ and, accordingly, they are depictedto have the same width in the drawing.

[0009] Subsequently, in a region which is not shown in FIG. 6A, a firstinterlayer insulation film of a resist material or the like, a coil in ashape of horizontal spiral on the first interlayer insulation film, anda second interlayer insulation film of a resist material or the like onthe coil are successively formed, the coil being provided at both endsthereof with an electrode.

[0010] A further plating base layer 35 of Ni₈₀Fe₂₀ having a thicknessof, for example, 0.1 micrometer is then formed on the write gap layer 34by a sputtering process, as shown in FIG. 6A.

[0011] Referring to FIG. 6B, a patterned resist layer 36 is then formedand, using the patterned resist layer 36 as a plating frame, an Ni₅₀Fe₅₀layer 37 having a thickness of, for example, 1 micrometer and anNi₈₀Fe₂₀ layer 38 having a thickness of, for example, 2.0 micrometersare successively formed by a plating process, to provide an uppermagnetic pole 39.

[0012] Referring to FIG. 6C, after the removal of the resist layer 36(FIG. 6B), exposed portions of the plating base layer 35 of Ni₈₀Fe₂₀,which are shown by the broken lines in FIG. 6C, are removed by ionmilling using Ar ions 40.

[0013] Subsequently, an Al₂O₃ film, as a protective film, is provided onthe entire face of the substrate 31 having a laminate structure offormed layers, although not shown in the drawing, and the substrate iscut and subjected to a slider making process which includes grinding foradjusting lengths of write poles, i.e., a gap depth, and polishing, tothereby produce a basic construction of a thin film magnetic head.

[0014] When the thin film magnetic head obtained as described abovereferring to FIGS. 6A to 6C was used to write a magnetic recordingmedium having a coercive force H_(C) of 3500 oersteds (Oe), it was foundthat an overwrite value was −27 dB.

[0015] However, since an overwrite value is generally regarded as beingpractical when it is −30 dB or lower, the conventional thin filmmagnetic head as described above was not appropriate as a thin filmmagnetic head for a recording medium of high recording density having acoercive force H_(C) of the order of 3500 Oe.

[0016] Thus, with the development of recent recording mediums having ahigher coercive force, it is necessary to use a material having a highersaturation magnetic flux density B_(S) for an upper magnetic pole core,or for an upper magnetic pole core and a lower magnetic layer,constituting an inductive thin film magnetic head, and with the need ofsuch a higher saturation magnetic flux density, it has been recognizedthat a magnetic thin film for the upper magnetic pole core and the lowermagnetic layer must have a B_(S) nearly equal to 2.0 T at a portion atwhich a magnetic flux is most concentrated.

[0017] As a magnetic thin film material meeting such a need of highersaturation magnetic flux density, CoNiFe materials were developed(Japanese Patent Application No. 2000-7487, which has not been publishedat the filing of the present application). The CoNiFe material hasmagnetic properties superior to those of 80 permalloy and 50 permalloy.For example, Co₆₄Ni₁₂Fe₂₄ has a saturation magnetic flux density B_(S)nearly equal to 2 T, and can provide a thin magnetic head having a headmagnetic field which is larger than that of conventional thin filmmagnetic head.

[0018] Nevertheless, a film of such a CoNiFe material, which is formedby an electroplating process, has an internal stress, which isdistributed in the plane of the formed film, of about 0.5 to 10×10¹⁰dyn/cm², which is large compared to 80 permalloy and 50 permalloy, andwhen it is formed into a film having a thickness of micron-order, itwill give rise to a problem that the formed film is prone to peel.Incidentally, a Co₆₄Ni₁₂Fe₂₄ film has an internal stress of about 7×10¹⁰dyn/cm².

[0019] When a magnetic thin film is peeled, the peeled magnetic thinfilm, which represents a metal piece, damages other part or parts of amagnetic head, or leads to the generation of dust in another process,and causes trouble to an apparatus for manufacturing a magnetic head.Consequently, it has been difficult to use a CoNiFe material as amagnetic material for a thin film magnetic head.

SUMMARY OF THE INVENTION

[0020] Thus, the invention aims to enhance a writing capacity of a thinfilm magnetic head by the use of a magnetic film of high saturationmagnetic flux density having a small thickness.

[0021] A thin film magnetic head according to the invention ischaracterized by comprising a plating base layer, which makes up anupper magnetic pole of the thin film magnetic head, made of a magneticfilm having a saturation magnetic flux density of 1.2 teslas (T) orlarger, more preferably 1.9 teslas or larger. Thus, the inventionprovides a thin film magnetic head comprising a substrate, a lowermagnetic pole provided on the substrate, a write gap layer located onthe lower magnetic pole, and an upper magnetic pole located on the gaplayer, the upper magnetic pole including a plating base layer in contactwith the gap layer, wherein the plating base layer of the upper magneticpole is made of a magnetic film having a saturation magnetic fluxdensity of 1.2 T or larger, more preferably 1.9 teslas or larger.

[0022] Preferably, the thin film magnetic head of the invention furthercomprises a thin magnetic film having a saturation magnetic flux densityof 1.2 T or larger, more preferably 1.9 teslas or larger, between thelower magnetic pole and the write gap layer.

[0023] Preferably, at least one of the plating base layer and the thinmagnetic film located between the lower magnetic pole and the write gaplayer is formed of a magnetic material of alloy containing one or moreof elemental Co, Ni, and Fe.

[0024] Preferably, at least one of the plating base layer and the thinmagnetic film located between the lower magnetic pole and the write gaplayer is formed of a sputtered or evaporated film.

[0025] Preferably, at least one of the plating base layer and the thinmagnetic film located between the lower magnetic pole and the write gaplayer has a thickness of 0.05 micrometer or more.

[0026] Preferably, the upper magnetic pole comprises an electroplatedfilm having a saturation magnetic flux density of 1.5 T or largerlocated on the plating base layer.

[0027] Preferably, the electroplated film is formed of a magnetic filmhaving a higher saturation magnetic flux density and a magnetic filmhaving a lower saturation magnetic flux density, the magnetic filmhaving a higher saturation magnetic flux density being located closer tothe plating base layer.

[0028] The invention can provide a magnetic storage device using thethin film magnetic head according to the invention, the magnetic storagedevise having an enhanced recording capacity and being capable ofadequately writing record to a recording medium having a high coerciveforce.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects and advantages of the invention willbe well understood and appreciated by a person with ordinary skill inthe art, from consideration of the following detailed description madeby referring to the attached drawings, wherein:

[0030]FIG. 1 schematically shows the principle of the invention,

[0031]FIGS. 2A to 2C illustrate the manufacture of a thin film magnetichead of a first embodiment of the invention,

[0032]FIG. 3A illustrates a thin film magnetic head of a secondembodiment of the invention,

[0033]FIG. 3B shows curves of magnetization of the upper magnetic poleof the magnetic head of the second embodiment,

[0034]FIG. 4 is a schematic sectional view of a thin film magnetic headof a third embodiment of the invention,

[0035]FIG. 5 is a schematic sectional view of a thin film magnetic headof a variant of the third embodiment, and

[0036]FIGS. 6A to 6C illustrate the manufacture of a conventional thinfilm magnetic head.

DETAILED DESCRIPTION OF THE INVENTION

[0037]FIG. 1 schematically shows the principle of the invention. In thisdrawing, a lower magnetic pole 2, a write gap layer 3, a plating baselayer 4, and a film 5 of high saturation magnetic flux density aresuccessively formed on a substrate 1, with the plating base layer andthe film 5 of high saturation magnetic flux density forming an uppermagnetic pole 6. The substrate 1 may be an Al₂O₃—TiC substrate, asearlier described, or the like. The write gap layer 3 may be formed ofAl₂O₃ or the like, also as described earlier.

[0038] The thin film magnetic head according to the invention uses, asthe plating base layer 4, which forms the upper magnetic pole 6 of thethin film magnetic head, a magnetic film having a saturation magneticflux density of 1.2 T or larger. By the use of the plating base layer 4of saturation magnetic flux density of 1.2 T or larger, the thin filmmagnetic head of the invention can achieve improved overwritingproperties even if the film 5 of high saturation magnetic flux densityhas a small thickness.

[0039] In addition, when such a film having a saturation magnetic fluxdensity B_(S) of 1.2 T or larger is also provided at the side of thelower magnetic pole 2, the thin film magnetic head of the invention canhave a further improved magnetic properties.

[0040] It is preferable that the magnetic film having a saturationmagnetic flux density B_(S) of 1.2 T or larger has a thickness of 0.05micrometer or more in order to display an improvement in the saturationmagnetic flux density.

[0041] Referring to FIG. 2, the manufacturing process of a thin filmmagnetic head of a first embodiment of the invention will be described.

[0042] As illustrated in FIG. 2A, a first plating base layer 12 ofNi₈₀Fe₂₀ and a lower magnetic pole layer 13 of Ni₈₀Fe₂₀ are successivelyformed on a TiC substrate 11 provided with an Al₂O₃ film (not shown)(also called Al₂O₃—TiC substrate). The surface of the magnetic polelayer 13 is then planarized, and a write gap layer 14 consisting ofAl₂O₃ is formed thereon by a sputtering process. There is a case wherethe write gap layer 14 is subsequently patterned together with the lowermagnetic pole layer 13 of Ni₈₀Fe₂₀ and, accordingly, they are depictedto have the same width in the drawing.

[0043] Subsequently, in a region which is not shown in FIG. 2A, a firstinterlayer insulation film of a resist material or the like, a coil in ashape of horizontal spiral on the first interlayer insulation film, anda second interlayer insulation film of a resist material or the like onthe coil are successively formed, the coil being provided at both endsthereof with an electrode.

[0044] A second plating base layer 15 of Co₆₃Ni₁₁Fe₂₆ having a thicknessof 0.05 micrometer or more, for example, 0.1 micrometer, is then formedon the write gap layer 14 by a sputtering process, as shown in FIG. 2A.It should be noted that, since a CoNiFe film formed by a sputteringprocess has a saturation magnetic flux density B_(S) which is a littlelower than that of a CoNiFe film formed by an electroplating process,the second plating base layer 15 has a little larger Fe compositioncompared to the Co₆₄Ni₁₂Fe₂₄ film referred to above, in order to achievea saturation magnetic flux density B_(S) of about 2 T.

[0045] Subsequently, a patterned resist layer 16 is then formed, asillustrated in FIG. 2B, and using the patterned resist layer 16 as aplating frame, an Ni₅₀Fe₅₀ layer 17 having a thickness of, for example,1 micrometer and an Ni₈₀Fe₂₀ layer 18 having a thickness of, forexample, 2.0 micrometers are successively formed by a plating process,to provide an upper magnetic pole 19.

[0046] The resist layer 16 is then removed and, thereafter, asillustrated in FIG. 2C, exposed portions of the second plating baselayer 15 of Co₆₃Ni₁₁Fe₂₆, which is shown by the broken lines in thedrawing, are removed by ion milling using Ar ions 20.

[0047] Subsequently, an Al₂O₃ film (not shown), as a protective film, isprovided on the entire face of the substrate 31 having a laminatestructure of formed layers, and the substrate is then cut, and issubjected to a slider making process which includes grinding foradjusting lengths of write poles, i.e., a gap depth, and polishing, tothereby produce a basic construction of a thin film magnetic head, as inthe manufacture of conventional thin film magnetic heads.

[0048] When the resultant thin film magnetic head was used to write amagnetic recording medium having a coercive force H_(C) of 3500 oersteds(Oe), it was found that an overwrite value was −35 dB, which wasimproved and was larger by 8 dB compared to the overwrite value of thethin film magnetic head using the Co₆₄Ni₁₂Fe₂₄ film formed by anelectroplating process referred to above, and was sufficiently meet therequirement of practical overwrite value of −30 dB or smaller.

[0049] Formerly, an Ni₈₀Fe₂₀ layer was used as a plating base layer bypaying attention only to ease of the production of thin film magneticheads. In contrast, in the thin film magnetic head of the firstembodiment of the invention described above, attention is paid to asaturation magnetic flux density of a plating base layer, to which noattention has been paid hitherto, and the magnetic film having asaturation magnetic flux density of 2.0 T is used as the plating baselayer, so that the thin film magnetic head can have improved writingproperties and a high recording capacity.

[0050] Referring to FIG. 3, a thin film magnetic head of a secondembodiment of the invention will now be described.

[0051]FIG. 3A schematically shows a sectional view of a thin filmmagnetic head of a second embodiment of the invention. The process formanufacturing it is the same as that for the thin film magnetic head ofthe first embodiment and, accordingly, is not described here.

[0052] The thin film magnetic head of the second embodiment of theinvention uses, as a film of high saturation magnetic flux densityforming an upper magnetic pole, a layer 21 of Co₆₄Ni₁₁Fe₂₅ having asaturation magnetic flux density B_(S) of about 2 T. Other components inthe thin film magnetic head of this embodiment are the same as those ofthe first embodiment as described above, and are indicated by the samereference numerals in FIGS. 2A to 2C.

[0053]FIG. 3B shows curves of magnetization of the upper magnetic polein the second embodiment, which consists of a plating base layer 15 ofCo₆₃Ni₁₁Fe₂₆ and the upper magnetic pole layer 21 of Co₆₄Ni₁₁Fe₂₅. Acoercive force H_(C) in the direction of axis of difference ofmagnetization of the Co₆₃Ni₁₁Fe₂₆ film 15, which was formed by asputtering process, is 33 Oe, which is very large, whereas a coerciveforce H_(C) in the direction of axis of difference of magnetization ofthe Co₆₄Ni₁₁Fe₂₅ film 21, which was formed by an electroplating, is verysmall. Accordingly, the coercive force H_(C) in the direction of axis ofdifference of magnetization of the entire upper magnetic pole ispractical value of 2 Oe, and inferior magnetic properties of the platingbase layer is compensated. In other words, a magnetic material forming athin film magnetic head must have a coercive force H_(C) in thedirection of axis of difference of magnetization of 10 Oe or smaller,more preferably 2 Oe or smaller, and, in the second embodiment of theinvention, the upper magnetic pole has a coercive force of 2 Oe as awhole, which is in a practical range, so that it can adequately meetsuch a need.

[0054] On the other hand, both films 15 and 21 have a saturationmagnetic flux density B_(S) of about 2 T, and the upper magnetic poleformed of these films also has a saturation magnetic flux density B_(S)of about 2 T as a whole. Accordingly, the entire upper magnetic pole inthe second embodiment can have a saturation magnetic flux density whichis improved by about 0.1 T compared to a magnetic pole using a platingbase layer of low saturation magnetic flux density, to thereby have ahigh recording capacity.

[0055] Thus, in the second embodiment of the invention, the film of highsaturation magnetic flux density forming the upper magnetic pole is madeof the Co₆₄Ni₁₁Fe₂₅ film having a large saturation magnetic flux densitythan that of an Ni₅₀Fe₅₀ film and, accordingly, the upper magnetic polecan achieve sufficient magnetic properties even if it has a littlesmaller thickness.

[0056] In addition, the Co₆₄Ni₁₁Fe₂₅ film has a saturationmagnetostriction λ, which is smaller than that of an Ni₅₀Fe₅₀ film andis close to that of an Ni₈₀Fe₂₀ film. From this point of view, magneticproperties of the Co₆₄Ni₁₁Fe₂₅ film are not degraded by strain inducedduring the processing, even if the film is formed in a little largerthickness.

[0057] A thin film magnetic head of a third embodiment of the invention,which will now be described by referring to FIG. 4, illustrates aschematic sectional view of the magnetic head. In this embodiment, alayer 22 of Co₆₃Ni₁₁Fe₂₆ having a high saturation magnetic flux densityis provided on a lower magnetic pole 13 of Ni₈₀Fe₂₀. Other componentsand the formation thereof in the thin film magnetic head of thisembodiment are the same as those of the second embodiment as describedabove, and are indicated by the same reference numerals in FIG. 3A.

[0058] In this embodiment, following the formation of the lower magneticpole 13 of Ni₈₀Fe₂₀, the surface thereof is planarized, and a layer 22of Co₆₃Ni₁₁Fe₂₆ having a thickness of 0.05 micrometer or more, forexample, 0.1 micrometer, is then deposited by a sputtering process,after which the step of forming a write gap layer 14 and following stepsas earlier described for the second embodiment can be carried out.

[0059] Thus, in the third embodiment of the invention, the layer 22 ofCo₆₃Ni₁₁Fe₂₆, which has a saturation magnetic flux density B_(S) ofabout 2 T and is in contact with the write gap layer 14 of the lowermagnetic pole side, is provided. This layer 22 makes it possible toprovide, in combination with the layer 21 of high saturation magneticflux density of the upper magnetic pole, the thin film magnetic head ofthe embodiment with a still higher recording capacity.

[0060] There can be a variant of the thin film magnetic head of thethird embodiment of the invention and this is illustrated in a schematicsectional view of FIG. 5. In this variant, an additional upper magneticpole layer 23 of Ni₅₀Fe₅₀ is provided on the upper magnetic pole layer21 of Co₆₄Ni₁₁Fe₂₅ in the third embodiment. Other components and theformation thereof in the thin film magnetic head of this variant are thesame as those of the third embodiment as described above, and areindicated by the same reference numerals in FIG. 4.

[0061] In this variant, during the formation of the upper magnetic poleby an electroplating process using a patterned resist layer as a platingframe, an additional upper magnetic pole layer 23 of Ni₅₀Fe₅₀ having athickness of, for example, 1 micrometer may be formed following theformation of the upper magnetic pole layer 21 of Co₆₄Ni₁₁Fe₂₅ having athickness of, for example, 1 micrometer.

[0062] According to a current electroplating process, it is difficult,due to an internal stress and the like, to form, through simple steps, alayer of Co₆₄Ni₁₁Fe₂₅ having a stable thickness of 1 micrometer or morein a condition where good magnetic properties are preserved, and,consequently, there is a possibility that a thin film magnetic headusing such a layer of Co₆₄Ni₁₁Fe₂₅ cannot generate an adequate magneticfield. Contrarily, in the variant of the third embodiment of theinvention as described, since the additional upper magnetic pole layer23 of Ni₅₀Fe₅₀, which has a saturation magnetic flux density B_(S) ofabout 1.5 T, is provided on the upper magnetic pole layer 21 ofCo₆₄Ni₁₁Fe₂₅, the thin film magnetic head of this variant can generate asufficiently strong magnetic field.

[0063] As will be well understood by those skilled in the art, theinvention is not limited to the embodiments and variant as describedabove, and various modifications and changes may be made withoutdeparting from the scope and spirit of the invention.

[0064] For example, although the above embodiments and variant use aCo₆₃Ni₁₁Fe₂₆ layer as a magnetic film of high saturation magnetic fluxdensity to be provided on the plating base layer of the upper magneticpole side or the lower magnetic pole, the magnetic film of highsaturation magnetic flux density in the invention is not limited to aCoNiFe layer having such a composition, and may be formed of a materialselected from various CoNiFe materials having different compositions.

[0065] Further, the magnetic film of high saturation magnetic fluxdensity in the invention is not only formed of a CoNiFe material butalso may be formed of another material, provided that the anothermaterial has a saturation magnetic flux density B_(S) of 1.2 T orlarger, more preferably 1.9 T or larger. For example, the magnetic filmof high saturation magnetic flux density may be formed of an FeAlNmaterial, which is a ferrous material having aluminum and nitrogenadded, Ni₅₀Fe₅₀ or the like.

[0066] Also, although the upper magnetic pole layer is made up of theCo₆₄Ni₁₁Fe₂₅ film in the second and third embodiments described above,the material for the upper magnetic pole layer in the invention is notlimited to a CoNiFe material having such a composition, and may beformed of a material selected from various CoNiFe materials havingdifferent compositions.

[0067] In addition, the material having a high saturation magnetic fluxdensity in the invention is not limited to a ternary metal material ofCoNiFe, and a material, in which Cr, Mo, and/or a non-magnetic metalelement, such as W, is added to the ternary CoNiFe, may be used as thematerial having a high saturation magnetic flux density. Although such amaterial based on CoNiFe and containing an additive element provide amagnetic film having a saturation magnetic flux density which is alittle lower than 1.9 T, the material can provide a magnetic film withan enhanced resistivity.

[0068] Also, although the Ni₅₀Fe₅₀ film is used in the variant of thethird embodiment described above, as an additional magnetic film tosupplement the thickness of the upper magnetic pole, the material forthe supplementation is not limited to Ni₅₀Fe₅₀, and various magneticmaterials may be used therefor. For example, a film of Ni₈₀Fe₂₀, whichhas a saturation magnetostriction λ smaller than that of the film ofNi₅₀Fe₅₀, despite a saturation magnetic flux density B_(S) smaller thanthat of the Ni₅₀Fe₅₀ film, can be used to have a thickness of 1micrometer or larger.

[0069] Also, although the upper magnetic pole in the second embodimentdescribed above is made up only of the layer of Co₆₄Ni₁₁Fe₂₅, a film ofNi₅₀Fe₅₀ or Ni₈₀Fe₂₀ may be laminated on the layer of Co₆₄Ni₁₁Fe₂₅ tosupplement the thickness of the upper magnetic pole.

[0070] Also, although the write gap layer in the first embodimentdescribed above is provided directly on the lower magnetic pole, amagnetic film having a high saturation magnetic flux density, such afilm of Co₆₃Ni₁₁Fe₂₆, may be provided on the lower magnetic pole by asputtering process, which makes it possible to improve the overwritevalue of the thin film magnetic head.

[0071] In addition, although the film of Co₆₃Ni₁₁Fe₂₆ is formed by asputtering process in the respective embodiments described above, theprocess for the formation of the film is not limited to a sputteringprocess, and an evaporation process may be used.

[0072] Further, although the embodiments described above illustrate asingle inductive thin film magnetic head, those skilled in the art wouldeasily understand that the invention could apply to an inductive thinfilm magnetic head of a composite thin film magnetic head in which theinductive thin film magnetic head and a magnetoresistive (MR) head arecombined.

[0073] Also, although the plating base layer is provided directly on theAl₂O₃ film of the Al₂O₃—TiC substrate in the above embodiment describedabove for simplicity, a thin film of Ti or the like may be interposedbetween the Al₂O₃ film and the plating base layer to improve adhesion ofthe plating base layer to the substrate.

[0074] As described, the thin film magnetic head according to theinvention, in which a film having a saturation magnetic flux density of1.2 T or larger is used as a plating base layer for the formation of anupper magnetic pole by an electroplating process, can have an improvedrecording capacity. Thus, the invention largely contributes to providinga thin film magnetic head adapted to recording in an increased frequencyand having an increased recording density and, further, to theperformance of magnetic storage devices in which an HDD device, or thelike, of high performance is incorporated.

1. A thin film magnetic head comprising a substrate, a lower magneticpole provided on the substrate, a write gap layer located on the lowermagnetic pole, and an upper magnetic pole located on the gap layer, theupper magnetic pole including a plating base layer in contact with thegap layer, wherein the plating base layer of the upper magnetic pole ismade of a magnetic film having a saturation magnetic flux density of 1.2T or larger.
 2. The thin film magnetic head of claim 1, wherein a thinmagnetic film having a saturation magnetic flux density of 1.2 T orlarger is provided between the lower magnetic pole and the write gaplayer.
 3. The thin film magnetic head of claim 1, wherein the platingbase layer is formed of a magnetic material of alloy containing one ormore of elemental Co, Ni, and Fe.
 4. The thin film magnetic head ofclaim 2, wherein the thin magnetic film is formed of a magnetic materialof alloy containing one or more of elemental Co, Ni, and Fe.
 5. The thinfilm magnetic head of claim 1, wherein the plating base layer is formedof a sputtered or evaporated film.
 6. The thin film magnetic head ofclaim 2, wherein the thin magnetic film is a sputtered or evaporatedfilm.
 7. The thin film magnetic head of claim 1, wherein the platingbase layer has a thickness of 0.05 micrometer or more.
 8. The thin filmmagnetic head of claim 2, wherein the thin magnetic film has a thicknessof 0.05 micrometer or more.
 9. The thin film magnetic head of claim 1,wherein the upper magnetic pole comprises an electroplated film having asaturation magnetic flux density of 1.5 T or larger located on theplating base layer.
 10. The thin film magnetic head of claim 9, whereinthe electroplated film is formed of a magnetic film having a highersaturation magnetic flux density and a magnetic film having a lowersaturation magnetic flux density, the magnetic film having a highersaturation magnetic flux density being located closer to the platingbase layer.
 11. A magnetic recording device comprising the thin filmmagnetic head of claim 1.